The present invention relates to a sport shoe sole, especially of the type used for running shoes, particularly for long distance running, and having a midsole of shock absorbing material disposed between an insole and an outer sole of wear resistant material, the midsole being provided with inserts for increasing the hardness characteristics thereof.
A running shoe with such a sole has been known from the U.S. Pat. No. 4,364,188. There, for a good damping of the high pressure and shock loads occurring especially in the area of the ball and in the area of the heel, in both these areas, always one island-shaped cushion is provided in the soft midsole, which is even softer than the remaining part of the midsole. For the purpose of controlling the damping and for the stabilization of the running characteristics in the heel area, there, adjoining the island-shaped cushion toward the inner (medial) side of the running shoe, several cylindrical plugs made of an elastic material that is harder than that of the midsole are inserted into the midsole. In order to be able to adapt the shoe to the specific requirements of the particular runner, plugs of variable hardness may be plugged into the bores of the midsole from the direction of the outer sole. Several such plugs may be molded onto a carrier and may be inserted jointly into the intermediate sole, whereby, after insertion, the carrier joins in forming a part of the outer sole.
The present invention has a principal object of improving a running shoe of the initially mentioned type with regard to the manner of fixing of the damping members in the sole, and enlargement of the area in which they are locatable as well as the degree of adjustability of their damping characteristics.
This object is achieved, in accordance with a preferred embodiment of the invention, by constructing the damping members as a plurality of exchangeable damping discs that are received in a cylinder and acted upon by a piston. As a result of the cylinder-piston-principal used, one will obtain a better fixation of the damping elements relative to lateral deflection in the soft midsole and, in addition, several damping discs of variable hardness or compressibility may be mounted one on top of the other, and, thus, almost any given damping or resiliency characteristic may be achieved.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with the present invention.